Favoritos de nwoeanhinnogaehr

I found this beefy mushroom growing in the lawn about 1.5 m from my compost bin. Nearby trees include Black Walnut (Juglans nigra) and Norway Spruce (Picea abies). An apple (Malus sp.) stump was nearby.

Despite the look of this mushroom, it is fresh and not at all slimy. Does anyone have any idea what genus or species this is (Boletellus sp. and Tapinella atrotomentosa have been suggested)? Do you think that it’s parasitized?

Bacteriophages and bacteria from saline ponds and lakes of southern Saskatchewan. A volume of fixed sample water, about a tenth of a ml in these environments, is concentrated by filtration onto a exceedingly fine filter, and stained with a fluorescent dye that lights up when docked on nucleic acids (both DNA and RNA). This makes the viruses and bacteria (and phytoplankton) visible for counting in an epifluorescence microscope. Even the smallest viruses become visible and countable.

But isn't the resolution of the light microscope a factor of ten too large to see viruses? The trick works according to the same principles that allow you to see and count stars that are 16000 light years away: because they are sources of bright light compared to the background. The stars appear substantial, but their real diameter is almost infinitely smaller than the size that they appear to your eye.
In these photos, bacteria appear relatively large. In the first photo, I count roughly 50 bacteria. But you can see that the viruses that are parasites of bacteria, or bacteriophages, are very much more abundant. There are between 25 and 30 bacteriophages for every bacterium. This has probably been the relative abundance of bacteria and their phages in these environments for 100s of millions or even billions of years. How this equilibrium is maintained is pretty much a mystery for the moment. More below (tomorrow).